Vacuum packing foods and refrigerating them helps preserve food freshness, texture, and taste. The two major methods for vacuum packing food bags in the home are using resealable bags, which require mechanical sealing strips to close bags, and heat-sealing machines that melt the sides of bags together. Both methods have their drawbacks. Heat-sealed bags lose a portion of the bag each time they are reentered and resealed. They also require a heat sealer to reclose an opened bag, which may not be available away from home. On the other hand, the mechanical seal of resealable bags adds cost to every bag. Further, most resealable vacuum bags require an air valve imbedded in their sides and special vacuum pumps that mate with the special air valves. These extra features and components not only add costs, but also take up valuable kitchen space. Eliminating the need for air valves, and the associated vacuum pumps or vacuum hoses, would minimize the cost disadvantage of resealable bag. Finally, resealable bags cannot be vacuum packed with heat sealing machines and still be resealable—until now.
If a resealable bag could be vacuum packed with a heat-sealing machine, and still be resealable, than users would only have to buy one type of bag, thereby saving cost and kitchen space. Heat sealing machines work by enclosing the open end of the bag in a small vacuum chamber, drawing air from the bag through via tiny passageways embossed into the plastic sides, and fusing the plastic sides together with a hot wire or tape once the air has been evacuated from the bag. A resealable bag does not naturally lend itself for use with heat-sealing machines the bag's mechanical sealing strip is not accessible during the air evacuation process. Hence, the sealing strip would normally have to be closed after extraction from the heat-sealer. However, doing this would allow some air to reenter the bag no matter how quickly the user closed the sealing strip. Thus to reliably vacuum pack a resealable bag using a heat-sealing vacuum packing machine, some means must be available to close the bags sealing strip, as least for a few seconds, until the user could permanently close the sealing strip once the bag is outside the machine.
The prior art is replete with various bag sealing systems that may be activated either automatically or on command. It is well known that mechanical devices can manipulate food items and vacuum bags while those objects are still inside vacuum chambers. Such manipulations can be performed on a bag's sealing strip. See, for example the patent by Cannon, T (U.S. Pat. No. 7,818,948) that applies a force through the wall of a flexible vacuum chamber to close the vacuum bag's sealing strip. However, most bag manipulation mechanisms are for heat sealing systems and are not designed to close resealable bags. No heat-sealing vacuum packing systems possess mechanisms for closing the sealing strips of resealable bags. Finally, the small size of the vacuum cavities typically found in home vacuum packing machines severely limits the space available for autonomous seal-closing mechanisms. The cross sectional dimensions of the vacuum cavities found in home heat-sealing systems are typically less than 10 mm by 25 mm, making it challenging to devise an economical autonomous seal closing mechanism to fit and operate within such a small space.
Thus there is a need for methods and mechanisms to economically vacuum pack resealable bags using heat-sealing vacuum packing machines.